A friend of mine went to NY for a vacation/employment and was held in the immigration and has been detained?

for the last 20hrs.Military people accompanied him for questioning. He was in a military training for only about 2 months somewhere between 2001-2002 due to an ailing back and went home. Im not sure if he left with proper discharge doents. I got his luggage now from the airport with his written authorization. What I want to know is where does the military people bring him and for how long will he be detained? what could be the worst thing that could happen. If anyone has an answer, i will really appreciate and coz its like im running blind. Will he be okay and not be tortured or mistreated? are they given decent accomodation like food and bed to sleep in? Im so worried....pls help with answering this question.